In recent years in the field of medicine, it is commonplace for a patient to utilize multiple medical institutions. In such a case, there is a possibility that accurate treatment cannot be performed without the data of other medical institutions. Therefore, progress is being made toward making databases of patient medical data to perform treatment quickly and accurately.
It is desirable to make databases also for the image data of X-ray imaging. Accordingly, it is desirable to digitize X-ray imaging images. In medical X-ray diagnostic devices, conventionally, imaging has been performed using silver halide film. To digitize the image data imaged on silver halide film, it is necessary to re-scan the imaged film by a scanner, etc., after developing the film which requires time and effort.
Recently, a method has been realized in which the image is digitized directly using a CCD camera of about one inch. However, for example, when the lungs are imaged, a region of about 40 cm by 40 cm is imaged; and therefore an optical device that condenses the light is necessary; and the device undesirably becomes large.
As a method that solves the problems of these two methods, an indirect conversion X-ray flat panel detector that uses an amorphous silicon thin film transistor (a-Si TFT) has been proposed. This X-ray flat panel detector is an indirect conversion X-ray flat panel detector in which the incident X-rays are converted to visible light rays by a scintillator, etc., and the converted light is changed to charge by the photoelectric conversion film of each pixel.
In the X-ray flat panel detector, the pixels are arranged in an array configuration having lengthwise and crosswise sides of several hundred to several thousand pixels each. Each pixel includes a switching TFT made of a-Si, a photoelectric conversion film and a capacitor. The pixels arranged in the array configuration also are called a TFT array.